It is a general objective of the invention to provide a safety device meant to prevent the accidental release of trailers towed by vehicles particularly farm tractors, a device installed on a straight part of a trailer tow bar. This device having a plate set precisely above a pinhead to avoid the release. The inventor wanted this attach to be adaptable to several tow bars particularly the ones utilized in combination with agricultural tractors and that the installation of the device be done only once on a tractor and that it would suit the majority of the trailers utilized.
Furthermore, the inventor wanted that the attach could be adapted easily to different sizes of tractor tow bars. This attach should be simple, affordable and durable and meet the higher standards of safety. Certain tow bars have a Z shape with a short straight part. It is a more limited objective to provide a handle installed on this straight part and comprising a superior plate on which pivots the plate to cover the pin, the handle side comprising rocking means to lock in place the plate when it covers the pin. The trailers utilized have a double hand attach through which passes the pin.
More specifically, the objective of this invention is to provide an eccentric locking latch comprising a limiting extension and a rocking part which when rocked causes the limiting extension to retain the plate in place. This latch prevents the releasing from its position of the superior plate during transport of a trailer.
A great advantage of the invention is its adaptability of installation to a great deal of tractors, especially that it does not necessitate movements along the tow bar nor vertical movement and that it comprises fitting screws. Furthermore, the way the device is conceived, one can unlock it with one hand only letting the other hand free. The device does not depend on a spring, increasing its durability and its liability, for springs are often quite breakable and not always as resistant. The superior plate can retain a great force.
1. Field of the Invention
This invention relates to the field of the safety in the attachment of trailers towed by vehicles, especially to secure a pin used to maintain a trailer towed by farm tractors or trucks, preventing the accidental release of the pin and diminishing this potential source of hazards.
2. Description of Prior Art
Certain types and techniques of construction of safety locks are utilized to secure a pin to retain a tractor or truck tow bar between double hand plates. Generally, what is commonly used nowadays is a safety pin <<Cotter Pin>> located at the base of a maintaining pin, the safety pin passing through a hole drilled in the pin. However, one embodiment utilizes a device 20 placed above a superior hand 26 of a double hand attach 22, the device comprises a safety plate 34 held by spring means above the maintaining pin 30. A shortcoming that we observe in the prior art is that there is no simple and independent devices or methods to permit to maintain a pin in place while there is a great force coming from the bottom when it travels in a rugged terrain or when tractors get stuck. The known spring type pin attachments have a great tendency to exit when bottom forces are practiced.
The following patents and patent application Publications illustrate such concepts.
CA 992791, shows a mechanism installed on a double hand of a trailer, made of a rectangular plate 22 rotating around a pivot to avoid the releasing of a pin during vibrations caused by the transport.
The plate is held in place by a spring and has a thickness 24 corresponding to the thickness of a head 20 of its pin. One has to apply a manual force to lift the plate in order to turn it.
U.S. Pat. No. 4,783,094, Shows a system installed on a straight bar of a certain type of tractors; a plate avoids the vertical movement of a pin 20. This system comprises a locking rod sustained by a spring. This rod restrains the movement of the system on the tow bar by penetrating a hole located in the tow bar. Because the holes are not always at the same distance one has to drill new holes at times. One has also to lift the rod to slide the system backward on a tow bar that fits.
U.S. Pat. No. 6,193,260: a device installed on a double hand of a trailer adapted to a maintaining pin meant to prevent the accidental loss of the pin and the trailer.
FR 2458410: a case including a lock held by a chain.